WO 2000/71185 A1 discloses a medicament ampoule with a plastic ampoule body in which a piston is initially held by the ampoule body with a clearance fit. After the piston and the interior space of the ampoule have been sterilized, the piston is displaced into an adjacent region of the interior space of the ampoule body where the piston together with the ampoule body forms a seal. The seal is broken by returning the piston to its initial position.
Infusion pumps based on the syringe pump principle are used for numerous medical applications to continuously supply medicaments at a constant or temporally variable rate. One example thereof is the treatment of diabetes mellitus by the continuous subcutaneous infusion of insulin. Miniaturized infusion pumps which operate according to the syringe principle have been developed for this purpose. One such pump is known, for example, from EP 985419 B1.
WO 0160434 A1 discloses a piston for use in ampoules for infusion pumps of this type. The piston has a basic body and a sealing element bonded to the basic body such as by glue, adhesive, welding, etc. In this case, the basic body is composed, for example, of a thermoplastic material such as polypropylene and the sealing element is composed of a thermoplastic elastomer such as Santoprene.
However, because of their specific properties, stoppers with sealing elements made of thermoplastic elastomers may not remain sealed for the entire required storage period of several years under changing climate conditions because they are permanently deformed under the pressure acting on them from the ampoule body. Furthermore, when an ampoule with a pressed-in stopper is stored for a relatively long period of time at a high storage temperature, a slow deformation of the ampoule body under the pressure acting on it from the stopper (i.e., creep) generally occurs, which also has a disadvantageous effect on the seal.
Embodiments described herein provide an ampoule for a flowable substance that overcomes these disadvantages.